


Insane In The Membrane

by nschimm (skullsulker)



Category: Invader Zim
Genre: AFAB reader - Freeform, Academia, College, F/M, Professor - Freeform, age gap, desperate student, gender neutral reader, i mean you’re both Of Age so it’s not like weird, student
Language: English
Status: Completed
Published: 2020-02-10
Updated: 2020-02-10
Packaged: 2021-02-28 07:13:42
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,771
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22649950
Author URL: https://archiveofourown.org/users/skullsulker/pseuds/nschimm
Summary: Membrane was a hardass professor when it came to his class, but you were convinced that you could get a better grade on your paper with a little added persuasion.
Relationships: Professor Membrane/Reader
Comments: 6
Kudos: 130
Collections: Fics I like UwU





	Insane In The Membrane

**Author's Note:**

> special thanks to my membrane fucker discord chat for helping me solidify ideas. fic title comes from this song:  
> https://youtu.be/RijB8wnJCN0

You went into the final  _ thinking _ you had studied hard enough. As intense as Membrane’s subject could be, you were boasting a B in the class thus far.  _ Surely _ this exam would be like the previous ones. Why on earth would he throw you - and all the other students for that matter - a curveball?

“To test how comprehensive your knowledge is!” was Membrane’s answer as he handed out the essay prompt.

A number of students swore under their breath. All of the quizzes had been multiple choice, but now you had to pull a paper explaining the pros and cons of heavily manufactured biomechanical body parts out of your ass? 

“Fuckin’ ridiculous,” you murmured. The student next to you nodded in agreement. Still, you churned out your essay to the best of your ability. Your hand was cramping up, but you wanted to be as thorough as possible in order to get the grade, and maybe even impress him.

When it came to Membrane, you were a little bit of a teacher’s pet. Whenever you saw that he left a positive mark on your assignments, you got butterflies in your stomach. You liked his attention. A number of students fawned over him, which you certainly understood. He had a manic, mysterious energy paired with a deep voice that made your heart flutter. You’d never admit it, though. Too many  _ other _ students hated his guts. Which you also understood, as his classes were some of the most rigorous on campus - but still, the idea that some of your friends might look at you differently if you admitted your attraction to him was… not great. So you kept it to yourself.

“Thank you, Professor Membrane,” you said as you turned in your paper. “See you in a few days!”

“Yes yes, very good,” he mumbled. Something on his computer screen had him deep in thought.

You sighed and left the lecture hall feeling apprehensive about the test.

-

The next week, after he demonstrated what  _ not _ to do if your robotic appendage glitches and crushes something, he set the graded essays in a neat pile on the table at the very front of the lecture hall.

“I was very pleased with some of what I read!” Membrane remarked. “Many of you have an impressive understanding on why cybernetic limbs can  _ NEVER _ be produced on a large scale!”

You swallowed the dry lump in your throat. In your essay, you made the exact opposite argument. 

Feeling defeated, you trekked behind the other students lining up to retrieve their papers. When you saw yours, your stomach dropped.

Failure.

Stepping to the side, you looked up at Membrane’s unreadable expression.

“Professor,” you began, “Can I talk to you about my grade?”

He looked down, then took your paper so he could quickly read it once more.

You continued, “I feel like I backed up my argument pretty well, even if we disagr-”

He tutted and held a gloved finger to your face.

“Return to your seat,” he stated. “Come to my office hours if you wish to discuss it further.”

Another student piped up from behind you, “So, if we have questions, we can see you in your office?”

“No,” Membrane responded. “Only this one. The rest of you will deal with whatever grade you received.”

“But-”

He leaned forward with shocking speed to get  _ right _ in the her face. “ _ YOU WILL DEAL WITH WHATEVER GRADE YOU RECEIVED! _ ”

The student looked like she was about to cry. You couldn’t help but feel a bit tickled that you were getting special treatment, but concerned that your classmate was about to break down. You gave her a light pat on the arm in an attempt to comfort her, then made your way back to your seat.

-

There was time to go back to your dorm before Membrane’s office hours opened up. Once alone, you set your bag and books in their respective places. 

God, you needed a better grade on that paper.

You grabbed your laptop and looked up Membrane’s syllabus to see how his assignments were weighted; to assess the damages. Scribbling out the numbers on a notepad led to a  _ gravely _ disappointing realization.

If your grade remained an F, you wouldn’t be able to graduate on time.

A wave of terror and shame washed over you. You paced around your room wildly, trying to talk yourself into rational thinking.

“He’s- he’s a reasonable man,” you said, stopping to stare at your reflection in the mirror. “I’m sure if I explain my case - he doesn’t have to agree with me, obviously, but- but if I explain it, maybe…”

You trailed off, feeling slightly hopeless. All you could think of in that moment was the way he snapped at the poor girl earlier. 

“She was trying to reason with him,” you murmured. A weight of defeat made itself at home in your chest. If trying to explain herself resulted in  _ that _ reaction… You needed some insurance.

With a deep sigh, unsure of whether or not this would even  _ work _ , you put together an outfit that bordered on being suggestive.  _ A little added persuasion _ , you thought, stripping your old clothes and tossing them in your dirty laundry basket. You put on your new outfit - flatteringly tight in some places, showing a little skin in others. It certainly wouldn’t hurt to look cute while you plead your case.

That’s what you kept telling yourself as you made your way to his office, buried deep within the west wing of the science department. You clutched your essay in your hands, trying your best not to wrinkle the paper.

His office was just down the hall - you could tell because you heard a glass shattering and Membrane melodramatically scream, “ _ Noooooooooo! _ ”

You tapped the doorframe lightly. “Professor Membrane?”

He stood up from where he was mopping his spilled chemicals. For a moment he looked confused, then, upon remembering why you were there in the first place, gestured excitedly for you to come inside.

Slyly, you clicked the door shut behind you and flicked the lock. You weren’t sure how far you intended to go with this little plan, but some privacy might be in order. 

“Please, take a seat!” he announced. You sat in the chair across from his desk, shuffling it forward so that you could better see him.

“What is it that I can help you with? You were unhappy with your test score, correct?”

You nodded, sitting up a little straighter and batting your eyelashes. “I just feel as though, even if we disagree, I backed up my argument enough to warrant at least a passing grade.”

He hummed in response, plucking your essay from your hands and leaning back in his desk chair. You studied his face - what you could see of it, anyways - for any sign of disapproval.

“Why don’t I go over it with you?” you offered. “That way I can clarify any bits that might need it.”

“Certainly!” He placed your essay on top of some other papers and extended his metal arms, grabbing your chair and lifting it only to set it down on his side of the desk. You made an undignified noise at the sudden movement, then covered your mouth with your hand.

“There we are,” Membrane concluded, picking your papers back up. “Now, I believe I was…” He trailed off before jabbing a finger at the second paragraph of your essay. “Here.”

You nodded, scanning what you’d written up unto that point. 

“Anything the matter there?” you asked.

“No, not there. Although, you made a comment  _ here _ that confused me slightly.”

You leaned just a bit closer. 

“ _... Although given that biomechanical limbs have the potential to host a whole slew of problems, any new viruses that could arise should be carefully dealt with by highly specialized doctors - or in some cases, I.T. workers. _ ”

When you smiled at your dumb joke, Membrane shot you a quizzical look.

“I’m afraid I don’t understand.”

You sucked in a deep breath from between your teeth. “It’s- it’s stupid, really. I was trying to be funny.”

He blinked at you a few times.

An awkward chuckle crawled out of your chest. “Well, um, I said a  _ virus _ could arise, right? And since they’re, err, mechanical body parts, I made a pun..? A virus as in like, the kind that would make us sick, obviously, but also computer viruses that would need tech workers. Again, it’s stupid.”

Membrane looked back at the essay to reread the sentence. You felt yourself blush.  _ Stupid idiot _ , you thought, mentally kicking yourself.  _ You should’ve known he wouldn’t think a pun was funny. _

Once you’d silently resigned to your fate, you cast an embarrassed glance back at him.

Membrane’s shoulders were shaking. He was clutching his side with one of his hands, the other wrinkling your essay.

“Professor Membrane..?”

He gasped and let out the loudest belly laugh you’ve ever heard in your goddamn life. 

You jumped in your seat, startled at the sudden burst of noise. Pride began to well in your chest. It looked like you had a chance after all.

Membrane removed his goggles and set them on his desk so that he could wipe a stray tear from his eye. 

“Goodness,” he said, finally calming down enough to speak. “I don’t believe any student I’ve ever had has even attempted to make me laugh in their papers. Well done. I’ll have to use that joke on my kids sometime.”

You couldn’t help but grin. “Kids? How old?”

He sighed and leaned back in his chair, setting your paper down on his desk. “Oh, my poor, insane son is about eighteen now, and my daughter is sixteen. Quite a handful, those two.”

_ Insane son? _ you thought. Deciding not to pry, you went for flattery instead.

“Are either of them lucky enough to have your eyes? I can’t believe you’ve kept them hidden behind those goggles all this time.”

He chortled, and you were happy to see a hint of pink against the tips of his ears. “Well- thank you.” Membrane cleared his throat and picked your paper back up. “My daughter does, yes.”

You smiled politely. “Lucky her.”

He resumed reading your paper, asking the occasional clarification question as he moved along. On about the third question, you leaned towards the paper to read it as well, curving your spine slightly and resting a hand on his knee. You felt his body stiffen a bit in response, but you made no move to retreat. To your pleasant surprise, he didn’t either. 

You explained your points in the essay, keeping your hand lingering on him the entire time. You looked up at him once you were finished, smiling sweetly, putting on the most innocent face in the world.

Membrane was beyond flustered. You could practically see the steam rising from the top of his head - the poor man was probably hot enough to run a fever.

You ran your hand up his knee  _ oh so slightly _ . “Professor, are you alright?”

He sputtered in response, desperately trying to reboot and focus on the task at hand. “Yes! Yes, of course, I’m alright.”

“Would you like me to remove my hand?”

There was a beat of silence. You were hoping he’d say no, but you figured it’d be better to check than leave it up to chance. There was always the possibility that this could go haywire.

“I…” he paused, eyes darting to the side. “I don’t mind it.”

You let out a breath you didn’t know you were holding. “Okay.”

“Alright.”

“Excellent.”

He tried his best to focus back on your essay. You read along with him, leaning closer and closer while toying with the inseam of his slacks.

“Okay,” he said, letting out a short huff. “I think I could raise the grade on your paper.”

“Oh, wonderful!” you said, squeezing his thigh. “I really appreciate it.”

He chuckled lightly, then scribbled something on a sticky note, pressing it onto his laptop screen. 

Membrane sat back in his chair, apprehensive. Neither of you knew what to do next.

You cleared your throat and sat back, removing your hand from his leg. The two of you looked around the room without saying anything to each other, trying to stave away the awkwardness. 

You sucked in a deep breath, deciding that you might as well plunge in if you already got the grade.

“I find you  _ very _ attractive, Professor.”

He laughed, sounding somewhat embarrassed. “That’s kind of you to say.” There was a pause as he furrowed his brows in thought. “But, you do know that I’m going to raise the grade on your paper, yes? Whatever it was that you planned on doing to persuade me won’t be necessary.”

You nodded with a weak smile on your lips. “I know. I’m not doing it for the class.”

His eyes widened slightly. You noticed his fingers tighten against the arms of his chair.

Feeling encouraged by his reaction, you stood from your seat. As you moved towards him, fraction by fraction of an inch, you noticed his body language loosen, become more welcoming.

You wanted to see his face. You leaned down slightly so that you were eye level, skirting your fingers around the fabric of his lab coat that kept him hidden.

“May I?” you asked.

Membrane cleared his throat, blinking rapidly. “Oh- err, yes, I suppose. Just to warn you-”

You snapped the two buttons in front of his face open before he could finish his sentence. He must’ve seen your expression change.

“I know it can be alarming, that’s why I keep it covered. They’re from lab accidents long ago.”

You traced the pad of your thumb over a small patch of scar tissue on his chin. “Does it hurt?” you asked.

He smiled. “Not anymore, thankfully.” 

“That’s good,” you murmured, cupping the side of his face. 

You took a long moment to appreciate what you saw. Of course you’d wondered what he was hiding under there in the past - surely everyone that met him did - but now you were one of the privileged few able to see it in person. 

His jawline was a sight to behold. It was sharp, peppered with stubble and working hard to accent his high cheekbones. The scars he seemed so worried about were slightly darker than his skin, skipping across his chin and the lower side of his left cheek. The wrinkles so common with men his age added stunning topography to his features, dipping around the corners of his eyes and mouth. You could fall in love with this man if you weren’t careful.

“It’s alright if you’ve changed your mind,” he suddenly said. “Again, I keep it covered for a reason.”

You made a noise of disbelief. “Are you kidding me? Jesus- if the reason you keep it covered is that none of your students would be able to focus on your lectures ‘cuz of how goddamn handsome you are, then  _ yeah _ , that would make sense. You seriously mean to tell me you’re self conscious about this?”

Membrane looked incredibly bashful at your statement, gluing his eyes to the ceiling and turning bright pink. “You… haven’t changed your mind, then?”

You couldn’t help but let out a short laugh. “I haven’t changed my mind, no.”

“Okay.”

“Alright.”

“Excellent.”

The two of you grinned at each other, overcome with nerves about the entire situation. 

To your relief, he leaned forward slightly, pressing a chaste kiss to your lips before pulling away.

“That was cute,” you said.

“I don’t want to be too forward.”

You smiled at his politeness. “Can I be? Forward, I mean.”

Membrane sucked in a sharp breath. “O-of course. That may be the only way we get anywhere.”

With a giggle, you sat down on his lap, each leg resting on the fabric of the chair outside of his thighs. His eyes widened, a sheepish grin plastered across his face. Slowly, you set one of your hands on the left side of his chest, feeling his heartbeat as it threatened to burst out of his body.

“Nervous?” you asked, leaning in to whisper against his ear.

“Y-yes,” he choked out. “A bit.”

You planted a soft kiss on the side of his face before nibbling gently on his earlobe, causing him to hiss in a breath. He let out a gentle groan as you took one of his hands and guided it to your waist, giving him permission to touch you. His thumb circled your hipbone while his other hand moved to run up your thigh. You hummed in satisfaction, scratching your nails against his shoulder. You sat back to appreciate the dreamy expression on his face before leaning in to kiss him.

It was gentle at first, much like the first one; but the longer the two of you stayed pressed together, the needier you grew. Membrane was desperately trying to fit his hands under your clothes, but you kept distracting him with nibbles to his lower lip. You were desperately trying to get his lab coat off of him, but he kept distracting you by grinding your hips down onto his erection. You were both flushed and sweating, absolute messes dissolving into libido.

“Wait a moment-” Membrane said, pausing to gasp for air. “How… how  _ much _ do you think you want to do?”

You finally managed to unclasp the last of his lab coat’s buttons. You peeled the garment off of him to rest your hands on his sides, warm and soft against his undershirt.

“Whatever you want,” you responded, giving him a light squeeze. “I don’t think I’ve been this into anybody before in my life.”

He laughed softly, running his gloved fingers over your arms. “Well, thank you. I could say the same.”

That sent the butterflies in your stomach into overdrive. You grinned like an idiot, grinding down on him and biting his neck. He let out a cute little moan and you added a bit of suction to the bite, happy to coax more sounds out of him.

“You keep your neck covered up, right?” you asked against his skin.

“I do,” he said, a slight waver in his voice.

That gave you no qualms about leaving a trail of hickeys down his throat, getting his grip on your body to tighten. You reached his collarbone, giving it a teasing bite before working your way up the opposite side of his adam’s apple with the same patience. You could feel his dick prodding you through his slacks.

He sat forward abruptly, resting you back against his knees. “One moment,” he said.

“Is something the matter?” you asked, watching as he hastily removed his gloves.

“No,” he said, holding you steady on his lap as he wheeled the chair over to the cabinet of his desk. He rooted around in it, fishing out a fresh pair. “I just wanted to use some new gloves in case there were any harmful chemicals on those.”

“Why wear any?” You pressed a hand against the cold metal of one of his mechanical arms. “These are pretty amazing, if you don’t mind me saying.”

“Oh, why thank you!” He slipped them both on quickly. “It’s just that I’d hate if the joints on my fingers snagged on anything while they were inside of you.”

The matter-of-fact way in which he told you made your stomach do a delighted flip. “R-really?” you asked, stammering for a moment.

“Mmhm!” Membrane responded, fiddling with a setting on one of his arms. The tips of his right index and middle fingers began vibrating rapidly, a gentle buzzing sound filling the room. “I don’t use this feature particularly often.” He mused to himself. “Glad I get the chance to try it again.”

You swallowed a lump in your throat. “Is that so?”

“Oh! Unless you’d prefer if I didn’t. It’s my understanding that many people use vibrators for a more enjoyable experience, but forgive me if I was being presumptuous-”

You kissed him again to cut him off. “I’m just impressed you had the foresight to install something like that.”

“Well,” he said sheepishly. “I put it in with the intention of using it as a back massager.”

“That is  _ precious _ ,” you said, shifting your legs to bite on his earlobe.

Membrane hummed in response, sneaking his vibrating fingertips between your legs, rubbing against the inseam of your jeans. You gasped in response, rocking against them gently. He laid his head back to look at you, watching your expression change as you dug your nails into his undershirt. 

“Want to get rid of some layers?” He asked, a new, hungrier tone in his voice.

You nodded feverishly. He pulled away and you began to work on the front of your jeans, pulling at the button and zipper. You were distracted from your task by Membrane tugging off his t-shirt, sending it flying to his desk. You stopped fiddling with your pants entirely to rest your hands against his chest, then down to his stomach. 

If there was one image that could encompass the best parts of a “dad bod”, you sincerely hoped it was that of Membrane’s. He had that “used to be a six pack until I started  _ buying _ six-packs, now I have something like a beer belly” paired with broad shoulders and enough pectoral muscle to sink your teeth into. You bit into your tongue at the sight, trying to keep your mouth from watering too much.

“Oh, wow.” you whispered, “You look  _ amazing _ .”

He smiled briefly. “Well- thank you. I do believe you were working on your pants..?”

The reminder made you grin, apologizing and undoing your zipper. You stood for a moment, faltering slightly and catching your balance as you tugged off your shoes and jeans, leaving you in your shirt and a  _ very _ cute pair of panties that you’d changed into earlier, “just in case”. As you straddled his hips once more, you noticed him fondle the hem of your shirt with his hands.

“May I..?” he asked.

“Sure,” you said, kissing him again.

His fingertips traced the skin under your shirt, grazing against your hips and ribcage. The hand with the vibrating fingertips tickled slightly against you. He hesitated under your bra, pausing as if to ask permission. You pulled away for a moment to tug your shirt over your shoulders. The surprised expression on his face made you laugh as you tossed the garment into the rapidly-growing pile of clothes. The second you returned to the position facing him, he pulled you forward to kiss him again, his non-vibrating hand gripping you tightly as he slipped the buzzing fingers between your legs once more. You whined against his lips. He grinned in response, pressing down on your clit a little harder, taking advantage of your open-mouthed gasp by curling his tongue against yours. You ground your hips down against his fingers, reveling in the sensation. Membrane smiled as you pulled your lips away from his, choosing instead to bury your face against the warm space between his neck and shoulder, biting him lightly to stifle the noises you were making. 

He rubbed quick circles with his fingers, pushing you over the edge, his other hand steadily pressed against your back. He held you in place as your legs began to shake, as your cries began to increase in volume. You dug your nails into his skin while your spine arched into his grip, muffling your screams in the crook of his neck, body twitching against his hands.

Membrane slowly removed his fingers from your crotch as you came down from your high. With a few adjustments, his fingers ceased vibrating and he was able to hold you as you relaxed against his torso. The muscles in your legs jumped slightly at random intervals. 

“You alright?” he asked against your ear. To your delight, he kissed the side of your face with a surprising amount of tenderness. 

“Mmhm,” you hummed, voice wavering slightly.

“Good,” Membrane responded, running his hand down your spine. “Because I’d like a turn.”

You lifted your face from his shoulder to grin at him, then nodded eagerly.

He helped you to your feet, standing shortly afterwards to rid himself of his slacks. You watched as he looked around for a moment before gathering a small pile of books, then placing them at the foot of his desk.

“Would you stand on these?” Membrane asked.

You obliged. He measured where your hips lined up, then requested that you step off so that he could add another book.

“What’s this for?” you asked.

“I would like to fuck you over the table, but I was worried that our height difference would make it uncomfortable for you. I’m just evening things out.”

You smiled, a mix of arousal and anxiety twisting in your stomach.

“You’ve got something to wrap it with, right?”

Membrane thought for a minute, then looked up excitedly. “Actually, I do! My labs have been working on a new brand of condom-” he cut himself off to dig through one of his desk drawers, pulling said condom out victoriously. “Here we are. Not only is it ninety-nine point  _ nine _ percent effective compared to the typical ninety-eight percent, it truly feels as though there’s nothing there. And it has miniscule pores that release lubricant as needed.”

You stared at him with teasing disbelief. “That’s pretty impressive. You’ll have to tell me more about it once we’re done.”

“Oh!” he said, seemingly forgetting that he was about to get his dick wet once he started talking about his work. “Right, of course.”

“Can I put it on you?” you asked.

Membrane stopped his process of tearing open the wrapper. The tips of his ears were bright pink again as he handed you the condom, still nestled in its casing. You took it, the material crinkling in your hands, and dropped to your knees in front of him. Carefully, you peeled the elastic of his boxers down, shifting your gaze from his eyes to his member. It was pleasantly thick with a length you could imagine fitting comfortably inside of you. Your mouth watered as you bit back a grin. You looked back up at Membrane, taking in his somewhat bashful expression.

“Nice dick, Doc.”

He laughed at the boldness of your statement. You gave him a minute to catch his breath, then removed the condom from its wrapper to slide it over his shaft. Membrane inhaled sharply at the contact. He let out a pleased noise as you slowly pumped his dick in your hand, feeling it up until it stood at full attention again.

You pressed the tip into your mouth experimentally. He let out a gasp, grabbing the back of your head and pushing you down without thinking. You floundered, pulling back and coughing. As he was apologizing profusely, your cough shifted into a laugh.

“Take it easy, my god,” you said. “You’re already gonna get some. No need to rush.”

Membrane pinched his brow, his shoulders shaking with embarrassed laughter. You took advantage of his distraction to return your mouth to his dick, giving it quick, short strokes with your hand as you took a few inches between your lips. He gasped again, this time propping his hands against the edge of the desk behind him. The corners of your mouth twitched upwards in a slight smile as you continued to work his member.

Within a few minutes of you hollowing out your cheeks, he pulled you away.

“I want you over the table,” he said with a newfound coldness in his voice.

You didn’t hesitate to jump to your feet, scurrying to the stack of books with Membrane hot on your tail. You stepped up, facing away from him, and bent over slightly.

“Is this alright?” you asked.

He swallowed audibly. “That’ll do just fine.”

Membrane ran his hands over your sides, squeezing your hips and ass as the mechanics of his arms whirred. You propped yourself on your elbows, dipping your head down bashfully.

He ran the head of his cock slowly against your slit to test the waters. When you whimpered and moved back against him, Membrane took the initiative to press himself inside.

You practically  _ howled _ at the sensation, him filling you up all at once making your toes curl in delight. Membrane leaned forward to muffle his grunts against the skin of your shoulderblade, resting his forehead against you. Once you both got used to the sensation, he pulled out a little bit only to push back in, the hitch of his hips making both of you lose your breath.

You couldn’t help yourself in eagerly backing against him. He held you by the hips to force you still, laughing quietly as he stood back to look at the way you twisted beneath him.

“Weren’t you just saying there was no rush? Quite hypocritical, are we?”

You squeaked in protest as he set a slow, agonizing pace. You wanted it  _ fast _ and  _ hard _ , but Membrane was more than content to stand back and trace his hands over your body as he took his sweet time.

This pace he set began another orgasm building inside you, slower this time, like a pot of water set to boil. You rocked into him despite his earlier chastising, his hips hitting you deeper as he swore under his breath. The sound of your whines filled the air just as much as the sound of your bodies’ wet slaps against each other. 

Membrane began to thrust faster against you, a telltale sign that this fling could end soon. You darted a hand to your clit in hopes of reigning that climax in before he did, furiously rubbing your fingers in the same quick circles Membrane had used earlier, chasing the high as he hit your g-spot again and again and again. 

The cry you let out was the loudest, most desperate one yet. Your knees practically buckled beneath you, the only thing keeping you standing being Membrane’s arm he held beneath your hips.

“Careful, careful,” he warned as he placed your torso more fully on his desk. “Hold yourself upright like this.”

You let out a weak, “Okay,” as he held one of your hands in his own. 

“Let me know if you want to stop now,” Membrane said with a hint of worry. “I can always finish myself.”

Shaking your head, you lightly pressed your ass against his erection. “I started it, I should finish it, too.”

You could practically hear his smile as he realigned himself, pressing his dick into you as slowly as he did at first. A quiet moan escaped you as the sensation filled you yet again. Membrane sighed contentedly, pulling himself in and out just like before, only this time with the urgency of someone that wanted to cum  _ right now _ .

As his pace quickened yet again, his hands squeezing your rear as he drilled into you, a question sprung into your mind. 

Between gasps and whimpers, you choked out, “Can- you- feel- me- with- those- arms-?”

He groaned from deep in his chest, emptying himself inside his own brand’s condom. Membrane sighed and held his hand against the desk to pause and steady himself before pulling out. The loss of his dick made you let out a noise of disapproval. 

“Yes.” he finally said. You heard him take a few steps back, followed by the sticky sound of him removing the condom, then the light  _ clunk _ of Membrane tossing it in his trash can. “I have sensory receptors embedded in the metal. Otherwise I’d have a hard time being able to tell how much strength I put into daily tasks.” 

You hummed, turning your face to the side so you could watch him fumble for his underwear. 

“Does it hurt?” you asked without thinking.

Membrane paused in tugging up his boxers, then pulled them on. “Sometimes, yes. That’s why our prosthetics aren’t on the market yet. Still working out the kinks.”

He pressed a hand against your back, signaling that it was time for you to stand. On shaky legs, you took his arm, letting him guide you to the pile of clothes you’d made earlier. Membrane helped you sort out yours from his, and you quietly dressed yourselves.

Once clothed, you faced him to ask, “Where does it hurt the most?”

Membrane paused before he had his lab coat all the way buttoned, leaving his face and upper chest exposed. “The joints, particularly the elbows.”

A concerned sigh escaped you. Rather than dwell on it, you stepped forward and on your toes to lean upwards, trying to kiss him. He still had to meet you halfway, angling his head downwards with a soft expression on his face. 

“It might be the faux ulnar nerve,” you said as you pulled away. “I have friends that struggle with their biological ones, maybe you have the same buildup of fluids as them?”

“Maybe,” he responded, thinking for a moment. “My god. Maybe you’re right.”

Membrane strode to his desk, jotting down what you said on a loose leaf of paper. You grinned, excited that your shot in the dark might’ve been able to help him.

“Hey,” you said again. “What are your office hours for next semester?”

He barely paused to regard you, jumping straight to his computer to compose an email, presumably to whoever was the bioengineer of his arms. “Not sure yet. Why don’t you take another one of my classes so we can chat again?”

You barked out a laugh, walking towards him to plant a peck on his cheek. “Absolutely not. Your courses are batshit insane.”

“Really?” he asked, halting his email writing process to turn and face you. “I thought they were quite reasonable.”

“Yeah, I don’t think so,” you said before kissing him again, firmly on the lips this time. “Maybe I’m just a bad student.”

“The worst,” Membrane mumbled. All at once, he snapped into work mode, buttoning his lab coat up to hide his face. “Out, out, out!” he said firmly. “Lots of science to be done!”

You snorted back a laugh, unlocking the door as he ushered you from his office. 

As you were waving goodbye, he leaned in to say, “I can send you my schedule for next semester, if you’d like.”

A smile crept across your face, your eyebrows darting upwards. “Well, we’ll see if I can pencil in a few meetings with you.”

Membrane sighed in exasperation. “Whatever you say. See you soon.”

“Bye, Professor.”


End file.
